Appearance

• Cesium is a soft metal with a silvery-gold color. It's solid at room temperature (68 degrees Fahrenheit) but melts easily at only 83 degrees Fahrenheit.
  
  

Spectral Lines

• Cesium has two prominent spectral lines in the blue region of the visible spectrum. These spectral lines were used to identify cesium in 1860.
  
  

Ionization Potential

• Cesium has the lowest ionization energy of the stable elements at 3.894 electron volts. This value is the amount of energy required to remove an atom's topmost electron.
  
  

Reaction With Water

• Cesium reacts violently with cold water and ice down to a temperature of -177 degrees Fahrenheit. Pure cesium must be stored in an airtight container to keep it from contacting water.
  
  

Reaction With Glass

• Cesium hydroxide (CsOH) is the strongest hydroxide base and will rapidly attack glass. Cesium is typically sold in the form of the much more stable compound cesium azide (CsN3).